At least 47 people were killed when a large explosion tore through a Shiite mosque in the southern Afghan city of Kandahar during Friday prayers.
Over 70 people are wounded, a Taliban official said.
A suicide bomber detonated his vest during Friday prayers at the Fatimeh Imam Bargah Mosque in Kandahar’s heavily populated District 1, eyewitnesses told The National.
“There must have been at least 300 to 400 worshipers inside, including women since this is the largest mosque and a centre for the community,” Ahmad, 29, a regular worshipper at the mosque said.
It came days after a suicide bomb attack claimed by ISIS on a Shiite mosque in the northern city of Kunduz killed 50 worshippers and left more than 100 injured.
“Today, there was also a Fateha prayer meeting being held in the memory of those killed in the Shia mosque attack in Kunduz last week, so the attendance was higher,” Ahmad said.
“The area is also a crowded neighbourhood, and has a large Shia population,” he added.
Ahmad, who did not wish to share his real name, missed prayers on Friday but rushed to the scene after hearing the explosion.
While he was not allowed to get too close, he shared images that showed several bodies alongside shattered glass and concrete across a bloodied floor.
“Many of my friends were inside when it happened, some are still missing and unaccounted for. We don’t know whether they are fine or hurt. The situation is so terrible,” he said.
Mr Ahmad said he rushed to the Mirwais Regional Hospital to search for his friends and to donate blood for survivors. At the hospital, he witnessed more horror.
“There were so many injured and bloodied people, but there weren’t enough doctors or nurses to help them. It was very crowded as everyone had come there to look for their loved ones, hoping to find them alive,” he said.
A doctor told AFP the hospital was "overwhelmed".
"There are too many dead bodies and wounded people brought to our hospital. We are expecting more to come. We are in urgent need of blood. We have asked all the local media in Kandahar to ask people to come and donate blood."
Shias of the Hazara ethnic group have long been persecuted against by the Taliban and ISIS.
A significant number of Hazaras continue to live in Kandahar, a province that is considered the political centre of the Taliban insurgency, despite the persecution they face.
“We are concerned and fearful of them, especially since they took control. They say one thing to our face, but we don’t know what they have planned for the Shias behind our backs,” Mr Ahmad said. “We can’t trust them.”
There was no immediate claim of responsibility.
The blast coming so soon after the Kunduz attack underlines the increasingly uncertain security in Afghanistan, as ISIS steps up operations following the Taliban victory over the western-backed government in Kabul in August.